1. Field of the Invention
The present invention relates to a method of immobilizing a biocatalyst in the form of a granular formed body by using a water-dispersible photo-crosslinkable resin.
2. Description of the Related Art
As the biocatalyst to be immobilized, there can be mentioned animal cells, mammalian cells, plant cells, microbial cells and enzymes.
Attempts have been made to produce valuable substances by immobilizing biocatalysts by various polymers, but since the number of immobilizing polymers having a high affinity with biocatalysts is limited, a practical utilization of this technique is difficult.
The conventional technique will now be described, with reference to an animal cell as an example.
Intensive investigations have been made into the producing of many valuable substances by culturing animal cells in liquid culture media and some thereof have been industrially utilized.
As the method of culturing an animal cell, there can be mentioned not only a culturing method in which an animal cell is merely suspended in a liquid medium but also a gel entrapping immobilization culturing method in which an animal cell is entrapped in an aqueous gel and the immobilized cell is cultured in a liquid culture medium to effect a propagation of the cell in the gel. The latter method is advantageous in various points. For example, the animal cell which is mechanically weak or brittle against changes of the liquid properties can be protected by a gel layer during the culturing, and a solid-liquid separation between the cell and liquid, which is necessary for an exchange of the culture medium or recovery of the intended product after the culturing, can be performed very advantageously. Furthermore, an industrial production system can be easily established. For example, the intended substance can be continuously obtained by filling the gel which includes the immobilized cell in a bioreactor. Therefore, serious research has been made into materials for and methods of immobilizing animal cells.
Since animal cells are weak and brittle, natural substances such as alginic acid, carrageenan, mannan and gelatin are used as the immobilizing gel, but since the durability of the gel strength is poor, these gels are not industrially utilized, and research has been made with a view to improving the durability thereof. For example, there can be mentioned a method in which the kind of the salt is changed, to improve the durability of the gel strength at the entrapping immobilization of an animal cell with alginic acid, a method in which an animal cell-immobilizing gel is caused to flow in a reactor, to prevent a breaking of the gel, and a method in which, after the inclusion of an animal cell and an alginic acid gel, a synthetic polymer film is formed on the gel surface. Under this background, the development of a method in which a gel capable of entrapping an animal cell by an industrially applicable simple means, which can be used stably, can be formed, is urgently required.